This invention is directed to elongated decorative and protective molding as used in the automotive industry, generally referred to in the industry as trim.
Body molding trim receives wide use in the automotive industry, for purposes of decoration and protection.
Trim is generally derived from petro-chemical stock, primarily in the form of polyvinyl chloride (PVC). The use of thermoplastic rubbers (TPR's) provides a number of significant practical advantages over PVC, owing to the absence of plasticizers in the rubbers, the characteristic of substantial non-shrinkage possessed by the rubbers, and the lower density and smooth running characteristics possessed by the rubbers which greatly facilitates extrusion. However, TPR's do not laminate with polyvinyl chloride, nor do TPR's bond to polyethylene teraphthalate such as that trademarked mylar so that it has not been possible to utilize existing techniques for the fabrication and decoration of trim, as presently utilized with PVC.
A previous method of joining molded components and plastic films, shown in U.S. Pat. No. 4,046,945, Feb. 13, 1979 Baxman et al, involves the use of a fluid cement having a two component polyolefin of high viscosity mixed at a temperature in the range of 160.degree. C. to 250.degree. C., including various filler materials, and applied as hot mix by brush to the surfaces to be joined.
The two-element polymer of Baxman et al suffers from the disadvantages that it must be applied in a fluid form to one of the surfaces to be joined, at an elevated temperature, and at the time of the joint is to be effected, so that a pre-prepared joining element such as a vinyl tape having an adhesive polymer backing does not appear feasible using the materials of Baxman et al.
In a recently issued patent U.S. Pat. No. 4,139,664 Feb. 13, 1979 Wenrick, there is shown a form of trim construction having a composite section including an extruded portion in which mechanical joining is effected by way of projecting teeth, supplemented by an adhesive bond. A construction of this type suffers the production disadvantage of being totally unsuited to production by a continuous high speed process directly associated with the extrusion of the base section. Furthermore, the selection of materials is greatly restricted, due to the mechanical forming characteristics required of the toothed portion, and the construction is theoretically redundant in using complementary securing means to attach two sections together.